Using the Astra Range as an example, but applies to other cars in the same age bracket.
Astra G - Separate radio code and immobiliser code (Security Code)
Astra H - One single code for security, immobiliser, radio, basically everything in the car
Astra J - One single security code for BCM, IPC and probably other things, but modules do a VIN check for security check not security code.
Astra K - No car pass at all is provided, has to be done online and it gets the code off the server and auto inputs it.
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